Electrical controlled dispensing system



Aug. 10, 1965 J. A. SAMP 3,199,729

ELECTRICAL CONTROLLED DISPENSING SYSTEM Filed Aug. 7, 1963 2Sheets-Sheet l o Q r O o JOSEPH A. SAMP jam/M ATTORNEY.

Aug. 10, 1965 J. A. sAMP ELECTRICAL CONTROLLED DISPENSING SYSTEM 2Sheets-Sheet 2 Filed Aug. '7, 1965 NQ N 6E m3 9! $1 ow $1 m9 0? v9 cm HATTORNEY.

United States Patent 3,19%729 ELEQTRECAL CGNTRQLLED DISPENSZNG SYSTEMJoseph A. Sarnp, Arlington Heights, lih, assignor to The Pure (Bilompany, Palatine, @hio, a corporation of @hio Filed Aug. 7, 1%3, Ser.No. 3%,445 9 tClaims. (Cl. 22226) This invention relates to electricalcontrol systems and, more particularly, to commodity dispensing systemswhich are actuated by any one of a plurality of switches and includeremote means for indicating the quantity of the commodity dispensed foreach switch. The control system of this invention is especially usefulin a truck loading terminal for dispensing petroleum products, i.e.,gasolines, fuel oils, etc.

Unattended truck loading terminals are frequently used in the petroleumindustry to dispense bulk quantities of petroleum products, such asgasolines (with or without additives), furnace fuel oils, diesel fuels,etc. The facilities of tiese terminals basically consist of a centralcontrol station which includes a totalizer console to record the amountsof the various petroleum products purchased by each account or customerof the terminal, and a plurality of remote loading islands. The loadingislands are relatively small curbings surrounding the equipment formetering, ticket printing, connecting the truck to the dispensing means(such as swivel-type loading arms), set-stop counting, and individualkey-operated switches for each account to initiate the flow of product.It is customary to equip the loading islands so that only one truck canload at a time, thus requiring a plurality of loading islands for eachterminal.

The expense of installing and maintaining the prior art electricalsystems of the truck loading terminals is excessive since the number ofelectrical conductors required between each loading island and thetotalizer console is over twice the number of the account key-operatedswitches on the island.

In the control system of this invention, the number of electricalconductors required between each loading island and the totalizerconsole are considerably reduced by utilizing electromagneticallyoperated step switches, which are well known in the electrical art. Theadvantages of the control system of this invention include thefollowing:

(1) Reduced installation cost with respect to both labor and material.

(2) Relatively simple circuitry for ease in installation, maintenanceand trouble-shooting, and

(3) Future accounts can be incorporated in the system without costlyadditions.

It is, therefore, the primary object of this invention to provide animproved, but simplified electrical control system. Another object ofthis invention is to provide a commodity dispensing system utilizingstep switches. Still another object of this invention is to provide animproved electrical system for unattended truck loading terminals fordispensing petroleum products, which system utilizes step switches toreduce the number of electrical conductors. These and further objects ofthe invention will be described or become apparent as the descriptionthereof herein proceeds and reference is made to the accompanyingdrawings in which a preferred embodiment of the invention is shown byway of example and in which:

FIGURE 1 is a schematic circuit'diagram of one of several loadingislands, and

FIGURE 2 is a schematic circuit diagram of the remote control totalizerconsole.

Referring to FIGURES 1 and 2, the numeral 10 represents a key box whichis located on the loading island and contains a plurality ofkey-operated switches, which are switches coupled to key lock tumblers.Each of the key-operated switches represents a separate account orcustomer of the terminal, and each account has a key which will operateonly its switch. It will be obvious that switch-actuating devices otherthan keys can be used, such as plastic cards perforated so as tocomplete an electrical circuit if inserted in the proper slot of key box13. It will be noted that the wiring is illustrated for only a few ofthe account switches and other associated electrical equipment to behereinafter described, for the purpose of simplicity and clarity.

Assuming for the purpose of illustration that the holder of the key forswitch 12 desires to purchase one of two grades of gasoline sold at theterminal, the island loading arm is coupled with the accounts truck, andthe key is then inserted in the key lock tumbler coupled to switch 12and turned to close switch 12. Switch 12 is a double-pole, single-throwswitch having contacts 14 and 16, which are connected to the positiveterminal of 115 volt DC. power supply 18 through conductor 20. Upon theclosing of switch 12, the terminal of stepping switch 22 correspondingto the specific account, i.e., terminal 2, is connected to the positiveterminal of power supply 18 through conductor 26, contact 14 andconductor 24, and thereby has electrical potential impressed on it. Theclosing of switch 12 also causes the energization of operating orstepping coil 22) of stepping switch 22, which is connected to thenegative terminal of power supply 18 through conductor 23 and resistor3%. This circuit is completed by interrupter spring contact 32,conductor 34-, contact 16, and conductor 2-1 which is in turn connectedto the positive terminal of power supply 18.

The energization of operating coil 26 cocks stepping switch 22 and opensinterrupter spring contact 32. Upon the opening of interrupter springcontact 32, coil 26 is deenergized causing the interrupter springcontact 32 to close and the wiper contact of stepping switch 22, whichis in the home position, to advance one step to the first terminal. Ifpotential does not exist at the terminal to which the wiper contact ofstepping switch 22 has advanced, operating coil 26 reenergizes and thewiper contact advances to the next terminal. This sequence is repeateduntil the wiper contact of stepping switch 22 reaches the terminal thathas electrical potential impressed on it to complete shunt circuit 36,thereby stopping the action of stepping switch 22 and maintaining thewiper in a fixed position.

Operating coil of stepping switch 22 is connected in parallel byconductors 28 and 38 to operating coil 4d of stepping switch 42 locatedin the totalizer console. Stepping switch 4-2 comprises contact levelsor banks 42A, 42B, and 42C, having contacts which are similar in numherand correspond to the contacts of stepping switch 22-. The wipercontacts of banks 42A, 42B, and 42C are mechanically connected so thatthey will step or rotate in synchronism. Since coils 26 and 40 areparallel connected, the wiper contacts of stepping switch 42 will stepin synchronism with the wiper contact of stepping switch 22 and stop intheir respective banks at positions corresponding to the position atwhich the wiper contact of stepping switch 22 stopped, i.e., terminal 2.

Assuming product permissive switch 44 is closed, it will be apparentthat as soon as the wiping contact of bank 42C has moved from its homeposition to terminal 1, coil of relay ll will tend to be energized. Thiscircuit is completed from the negative terminal of power supply 18through conductor 28, conductor 49, the wiper arm of bank 42C,permissive switch 44, conductor and conductor 2@ to the positiveterminal of power supply 18.

e ema However, relay 43 is of the time delay type and will not beoperated during the movement of the wiper of bank 42C, because theenergizing circuit for relay 43 is periodically broken by the movementof the wiper of bank 42C. Since no invention is claimed in using aspecific time delay and such relays are commonly found in electricalcircuits, the mechanism and operation of relay 4% will not be discussedin detail. However, as soon as the wiping contact of bank 42C has cometo rest, coil as will be energized after a predetermined interval toclose contacts 52 to connect the positive terminal of power supply 18 toregular grade gasoline set-stop switch 54 and premium grade gasolineset-stop switch 56 through conductor 20, conductor 58, contacts 52, andconductor 60.

The permissive switches, such as product permissive switch 4-4, arepresent so that an account can receive a specific product and additive,or no additive (determined by agreement with that account), or so thatboth product and additive services for a specific account can beconveniently locked out in the event that an account is cancelled, butmay still have the key to close the switch in key box 10. Set-stopswitches 54 and 56 are doublepole single-throw switches mechanicallyoperated by the set-stop lever on the loading island meters, not shownfor the sake of simplicity, which will automatically open after theaccount has received the quantity of the product pre-set on the islandmeters.

Again assuming for the purpose of illustration that the key holder ofswitch 12 desires to purchase regular grade gasoline, after insertinghis key and turning it to close switch 12, he pre-sets the set-stopcounter of the loading island meter to the amount of gasoline he desiresto purchase and actuates the set-stop lever to close set-stop switch 54.One contact of set-stop switch 54 is connected by conductors 62 and 64to solenoid-operated valve 66 and motor starter 68, respectively. Theclosing of set-stop switch 54 actuates solenoid-operated valve 66, whichcontrols the flow of regular grade gasoline, and regular grade gasolinepump motor starter 63. The circuits to solenoid-operated valve 66 andmotor starter 63 are completed by conductors 7t) and 72, respectively,and conductor 28 connected to the negative terminal of power supply 18.If either of set-stop switches 54 and d are closed before key-operatedswitch 12, time delay relay 48 prevents the premature energization ofthe motor starter and solenoid circuits as the wiper of bank 42C seeksthe terminal corresponding to key-operated switch 12. After apredetermined interval, time delay relay 48 closes contacts 52 toprovide potential at set-stop switches 54 and 56. The second contact ofset-stop switch 54 is connected to coil 74 of time delay relay 76 byconductor 30 so that the closing of set-stop switch 54 also causes theenergization of coil 74. This circuit is completed through conductor 82,and conductor 23 which is connected to the negative terminal of powersupply 18. The energization of coil 74 closes normally-open contact 84-of relay 76 to provide potential at meter pulse contact 86. Thenormally-closed contact 83 is opened upon energization of relay 76 toprevent a false homing operation of stepping switch 22 if the key shouldbe removed from key box prior to completion of the loading operation.

Pulse contact 86 is mechanically coupled to the island meter so that itcloses and opens once for each gallon of product passing through themeter. Therefore, during the flow of product passing through the islandmeter, pulse contact 86 sends pulses through conductor 90 to the wipercontact of bank 42A. Since the wiper of bank 42A stops at the terminalcorresponding to the contact or terminal at which the wiper of steppingswitch 22 stops, as hereinbefore described, the pulse from pulse contact86 is transmitted through the wiping contact of bank 42A and conductor92 to regular grade gasoline counter 94 of the holder of key-operatedswitch 12.

Counter 94 is a pulse-actuated digital counter which serves as atotalizer for the key holder of switch 12. The circuit to counter 94; iscompleted through conductor 96 and conductor 28, which is connected tothe negative terminal of power supply 18. Conductor preferably includesstray pulse protection device 98 which prevents a false registration onthe counters in the event that meter pulse contact 36 is closed at thestart of the loading operation, and which also protects counter 94against transient disturbances in the electrical supply system. Sincethe structure and operation of stray pulse protection devices are wellknown to those skilled in the art and no invention is claimed in using aspecific stray pulse protection device, the structure and operation ofstray protection device )8 will not be described in detail.

The procedure and operation of the system is the same as hereinbeforedescribed if the account should desire to purchase premium gradegasoline. In this event, setstop switch 56 will be closed to completethe circuits from one contact of switch 56 through conductor 100 tomotor starter M 2 of premium grade gasoline pump and conductor 163 tosolenoid-operated valve 124 in the pipe controlling the flow of premiumgrade gasoline. Pulse contact 106 of the premium meter will then beopened and closed to send pulses through conductor 168, which preferablyincludes stray pulse protection device 110, to wiper of bank 42B,conductor 112 to premium counter 114. The circuit to counter 11% iscompleted through conductor 116, conductor 96, and conductor 28, whichis connected to negative terminal of power supply 18.

After the amount of regular grade gasoline which was pro-set on theisland meter has passed through the set-stop counter, set-stop switch $4is automatically opened through mechanical means to shut off the productpump controlled by starter 63, de-energize solenoidoperated valve 66 andde-energize coil '74 of relay 76 so that relay 76 begins to time-out.The time delay is to provide potential at meter pulse Contact 86 untilthe island meter has fully stopped rotating. On timing-out, relay 76opens contacts 34 to remove potential from meter pulse contact 86, andcloses contacts $8 to provide potential at oft-normal contact 118 ofstepping switch 22. Git-normal contact 11? assumes an open position whenthe wiper of stepping switch 22 is in the home position and is closedwhenever the wiping contact is in any other position.

When key-operated switch 12 is opened by the removal of the key from keybox It the terminal of stepping switch 22 which corresponds to thespecific account loses potential and shunt 36 across coil 26 of steppingswitch 22 is open-circuited. Because, off-normal contact 118 is closedwhen stepping switch 22 is in any position except the home position, acircuit is completed to operating coil 26 through contact $8 of relay76, off-normal contact 118 and interrupter spring contact 32 so thatstepping switch 22 will step around to the home position. It will beapparent that stepping switch 42 will simultaneously step around to itshome position since interrupter spring contact 32 is also connected tocoil 4t) of stepping switch 42. The return to the home position of thewiper contacts of stepping switch 42 will result in the de-energizationof time delay relay 4%, which in turn opens contacts 52 to removepotential from set-stop switch 54 and consequently de-energize motorstarter 68 and solenoid-operated valve 66 through conductors s4 and 62respectively. The above-described shutdown-sequence of operation willalso take place after a customer has received a pre-set amount ofpremium grade gasoline.

Those familiar with the operation of gasoline truck loading terminalswill be aware of the fact that the gasoline purchased from the terminalmay be sold under different brand names, which differ from each otheronly in the specific additive combinations contained in the gasoline. Itis therefore advantageous to incorporate in the system hereinbeforedescribed means for adding different additive combinations to thegasolines purchased by the various customers. Again assuming for thepurpose of illustration that the key holder of key-operated switch 12 ispurchasing gasoline and that the terminal contains provisions forblending either of two additive packages with the dispensed gasoline,additive permissive switches 12% and 122 are connected to the terminalof bank 42C corresponding to the key holder of key-operated switch 12.If it was determined by agreement with said account that it is toreceive one of the additive combinations, the specific additivepermissive switch for that additive will be closed. For example, if thekey holder of switch 12 is to receive the additive controlled bypermissive switch 120, switch 12% is closed so that when the wiper armof bank 42C stops at position 2, coil 124 of time delay relay 125 isenergized. This circuit is completed from the negative terminal of powersupply 18, through conductor 28, the wiper arm of bank 42C, permissiveswitch 120, conductor 128, coil 124 and conductor 5% to the positiveterminal of power supply 18.

After a predetermined interval, contacts 130 of relay 126 are closed tosend energizing current through conductor 132 to actuate the additivepump and valve mechanisms which are similar to the gasoline pump andvalve mechanisms. Accordingly, details of these mechanisms have beenomitted from the description for the purpose of simplicity, andtherefore clarity. On the other hand, should it be determined that thecustomer is to receive the additive controlled by switch 122, thestopping of the wiper contact of bank 42C at position 2 will complete acircuit from the negative terminal of power supply 18 through wiper armof bank 42C, switch 122, conductor 134, coil 136 of relay 138, andconductor 5% to the positive terminal of power supply 18. After apredetermined interval, relay 133 is energized to close relay contacts14%} and send current through conductor 142 to the valve and pumpmechanisms for the second additive.

It is preferred to incorporate in the system means for deactivating thesame if the wipers on the respective banks of stepping switches 22 and42 should fall out of step. This can be accomplished by providing bothstepping switches 22 and 42 with an additional contact bank (i.e., 22Aand 42D, respectively) having contacts or terminals similar in numberand corresponding to the contacts on the first bank of switch 22 andwipers which are mechanically connected to the other wipers of therespective stepping switches. Contact level 22A of stepping switch 22 iswired so that every other point, starting with the home position isconnected together and the wiper arm is connected to the positiveterminal of power supply 18 through conductors 144 and 2t Contact level42D of stepping switch 4-2 is wire-d so that every other point, startingwith the position after the home position, is wired together. Thecontacts on bank 42D that are connected are connected by conductor 146to the contacts that are wired together on bank 22A. The wiper of bank421) is connected by conductor 148 to coil of lock-out relay 152 througha normally closed reset button 154. If stepping switches 22 and 42 fallout of step with each other, a circuit will be completed from thenegative terminal of power supply 18, through conductor 28, coil 150 oflock-out relay 152, reset button 154, conductor 148, wiper of bank 42D,wired-together contacts on bank 42D, conductor 146, wired-togethercontacts on bank 22A, wiper of bank 22A, conductor M4, and conductor 26)to the positive terminal of power supply 18. Coil 15d of relay 152 isthereby energized to open normally-closed contact 1156 and closenormally-open contacts 15%. The opening of contact 156, which is in thesupply circuit for t5 time delay relays 43, 126 and 13S, prevents thestarting of the product and additive pumps.

In the event that an open circuit connection should occur in the portionof the key switch circuit connected with the terminals of steppingswitch 22, the wiper arm will travel past each point and upon notfinding potential in any point, will return to the home position,rendering the system inoperative. If an open circuit connection shouldoccur in the portion of the key switch circuit connected with the coilcircuit of stepping switch 22, the wiper arm thereof will not leave thehome position, rendering the system inoperative.

Normally-open, spring-operated contact 1611* in conductor 162 isprovided in key box It) and connected so that if the cover of key box itis removed by unauthorized persons, lock-out relay 152 will be energizedto open the supply circuit for time delay relays 48, 126, and 138,thereby preventing the start-up or operation of the product and additivepumps. Lock-out relay 152 will remain energized until reset button 154is pressed. Conductor as also preferably includes normally-closed switch154 in the totalizer console. Switch 164; is opened when it is desiredto have the lock-out circuit inoperable while the cover of key box it?is removed for maintenance purposes.

Although this invention has been described in relation to specificembodiments, it will be apparent that obvious modifications may be madeby one skilled in the art without departing from the intended scope ofthe invention. For example, a diode may be series connected with each ofthe permissive switches to prevent stray currents from entering thepermissive circuits of one customer from another customer. However, itwill be apparent that the diodes will have to be eriodically replaced.The task of periodically replacing the diodes can be obviated byreplacing stepping switch 42; with one having a greater number ofcontact banks so that there is a contact bank for each additivecombination. The terminals of each of the additional contact banks willthen be electrically connected to a plurality of additive permissiveswitches, i.e., one for each account, which will be electricallyconnected to the additive control circuits, i.e., conductors 128 and134. In such a system diodes need not be included in conductors 128 and134. It will also be obvious that oil-normal contact 118 and associatedelectrical components, e.g., contacts 88 can be deleted from thesystern. In this modification, relays 58, and 138 are preferably withoutthe time delay feature and contacts of a time delay relay are includedin conductor 49. The coil of this time delay relay is connected betweenconductors 28 and 34. As a result of such a modification, the wipers ofthe contact banks will not return to a home position upon the opening ofset-stop switches 54 and 56, but will remain in contact with theterminals corre sponding to the last user of the system. Although thisinvention has been described in relation to a system for dispensing twogrades of gasoline and two additives, it will be obvious that it may bemodified to dispense any number of liquid products and additives for theliquid products. In fact, the control system of this invention may beused in systems other than those for dispensing liquids such as one fordispensing grain by using suitable indicating means in place of thecounters.

The embodiments of this invention in which an eX- clusive property orprivilege is claimed are defined as follows:

ll. In an electrical control system adapted to be actuated by any one ofa first plurality of switch means,

(a) a first selector switch including a first stepping means and a firstcontact bank having a first plurality of spaced contacts and a firstcontact arm adapted to successively engage said first contacts,

(b) said first stepping means being adapted to successively engage saidfirst contact arm with said first contacts,

(c) each of said first contacts being electrically connected to one ofsaid first plurality of switch means, said plurality of switch meansbeing electrically connected to a potential source, whereby one of saidcontacts has electrical potential impressed on it upon closure of one ofsaid switch means,

(d) a first circuit, including a potential source and said firststepping means, adapted to stop the movement of said first contact armwhen said first contact art is engaged with the contact havingelectrical potential impressed on it,

(e) a second selector switch including a second stepping means and asecond contact bank having a second plurality of spaced contacts and asecond contact arm adapted to successively engage said second contacts,said second contacts being simiiar in number and corresponding to saidfirst contacts,

(i) said second stepping means being adapted to successively engage saidsecond contact arm with said second contacts, said first and secondstepping means being electrically connected such that said first andsecond contact arms move in synchronism,

(g) a second circuit including a potential source, said second contactarm, said second contacts, and first time delay means, and

(h) a third circuit including a potential source andelectrically-actuated control means, said first time delay meansincluding switch means for closing said third circuit.

2. A system in accordance with claim 1 in which each of said first andsecond stepping means includes a stepping coil and said stepping coilsare parallel connected.

3. A system in accordance with claim 2 which includes at least oneindicating circuit containing an indicating circuit contact bank havinga contact arm mounted for movement in unison with said second contactarm and adapted to successively engage a plurality of spaced contactswhich are similar in number and correspond to said second contacts, eachof said indicating circuits including indicating means electricallyconnected to each of the contacts of the contact bank contained thereinand means electrically connected to the contact arm of the contact bankcontained therein for actuating said indicating means in response tomovement actuated by said control means.

4. A system in accordance with claim 3 in which said third circuitincludes at least one switch means adapted to control the fiow of afluid and the contacts on the indicating-circuit contact banks areelectrically connected to indicating means adapted to indicate quantityof fluid 5. A system in accordance with claim 4 in which each of saidfirst and second selector switches includes a 5 monitoring contact bankhaving a contact arm adapted to successively engage a plurality ofspaced contacts, the contacts on said additional contact banks beingsimilar in number and corresponding to said first contacts, the contactarms on said monitoring contact banks being mounted for movement inunison with the contact arms of the other banks of the respectiveselector switches, every other contact of each of said monitoringcontact banks being electrically connected such that difierent contactson the monitoring contact banks of said first and second selectorswitches are electrically connected, and a fourth circuit, including theelectrically connected contacts of said monitoring contact bankselectrically connected to each other, is adapted to open anormally-closed contact in said second circuit if the contact arms ofsaid monitoring contact banks do not move in unison.

e. A system in accordance with claim 5 in which said first, second andthird circuits include the same potential source.

'7. A system in accordance with claim 6 in which said second circuitincludes a second plurality of switch means, each of said secondplurality of switch means being electrically connected to a time delaymeans including switch means adapted to control the flow of a differentfluid, and there is an indicating circuit having the flow thereofcontrolled.

ii. A system in accordance with claim 7 in which said first contact armis movable from a home position and is adapted to successively engagesaid first contacts upon closing of one of said first plurality ofswitch means and said system includes means adapted to cause operationof said first stepping means to return said first contact arm to homeposition after a predetermined interval of time upon opening of theclosed switch means of said first plurality.

9. A system in accordance with claim 8 in which each of said indicatingcircuits includes stray pulse protection means.

References Cited by the Examiner UNITED STATES PATENTS RAPHAEL M. LUPO,Primary Examiner.

1. IN AN ELECTRICAL CONTROL SYSTEM ADAPTED TO BE ACTUATED BY ANY ONE OFA FIRST PLURALITY OF SWITCH MEANS, (A) A FIRST SELECTOR SWITCH INCLUDINGA FIRST STEPPING MEANS AND A FIRST CONTACT BANK HAVING A FIRST PULRALITYOF SPACED CONTACTS AND A FIRST CONTACT ARM ADAPTED TO SUCCESSIVELYENGAGE SAID FIRST CONTACTS, (B) SAID FIRST STEPPING MEANS BEING ADAPTEDTO SUCCESSSEVELY ENGAGE SAID FIRST CONTACT ARM WITH SAID FIRST CONTACTS,(C) EACH OF SAID FIRST CONTACTS BEING ELECTRICALLY CONNECTED TO ONE OFSAID FIRST PLURALITY OF SWITCH MEANS, SAID PLURALITY OF SWITCH MEANSBEING ELECTRICALLY CONNECTED TO A POTENTIAL SOURCE, WHEREBY ONE OF SAIDCONTACTS HAS ELECTRICAL POTENTIAL IMPRESSED ON IT UPON CLOSURE OF ONE OFSAID SWITCH MEANS, (D) A FIRST CIRCUIT, INCLUDING A POTENTIAL SOURCE ANDSAID FIRST STEPPING MEANS, ADAPTED TO STOP THE MOVEMENT OF SAID FIRSTCONTACT ARM WHEN SAID FIRST CONTACT ARM IS ENGAGED WITH THE CONTACTHAVING ELECTRICAL POTENTIAL IMPRESSED ON IT, (E) A SECOND SELECTORSWITCH INCLUDING A SECOND STEPPING MEANS AND A SECOND CONTACT BANKHAVING A SECOND PLURALITY OF SPACED CONTACTS AND A SECOND CONTACT ARMADAPTED TO SUCCESSIVELY ENGAGE SAID SECOND CONTACTS, SAID SECONDCONTACTS BEING SIMILAR IN NUMBER AND CORRESPONDING TO FIRST CONTACTS,(F) SAID SECOND STEPPING MEANS BEING ADATPED TO SUCCESSIVELY ENGAGE SAIDSECOND CONTACT ARM WITH SAID SECOND CONTACTS, SAID FIRST AND SECONDSTEPPING MEANS BEING ELECTRICALLY CONNECTED SUCH THAT SAID FIRST ANDSECOND CONTACT ARMS MOVE IN SYNCHRONISM, (G) A SECOND CIRCUIT INCLUDINGA POTENTIAL SOURCE, SAID SECOND CONTACT ARM, SAID SECOND CONTACTS, ANDFIRST TIME DELAY MEANS, AND (H) A THIRD CIRCUIT INCLUDING A POTENTIALSOURCE AND ELECTRICALLY-ACTUATED CONTROL MEANS, SAID FIRST TIME DELAYMEANS INCLUDING SWITCH MEANS FOR CLOSING SAID THIRD CIRCUIT.